Under Diocletian's Tetrarchy reform, the easternmost part was broken off from Mauretania Caesariensis as a separate small province, Sitifensis, called after its inland capital Sitifis (Sétif) with a significant port at Saldae (presently Béjaïa).

Religion

Among the ruling class, Trinitarian Christianity was replaced by Arianism under the Germanic kingdom of the Vandals, which was established in 430, when the Vandals crossed the Strait of Gibraltar. The Vandal kingdom was extinguished by the Byzantine armies around 533, but most of Mauretania Caesariensis remained under the control of local Moorish rulers such as Mastigas, and it was not until the 560s and 570s that Byzantine control was established in the interior. The Byzantine Exarchate of Africa was in its turn overrun by the Muslimcaliphate under the Umayyad dynasty, ending Late Antique Roman culture there; most of former Mauretania Caesariensis became part of the westernmost Islamic province, henceforth called (al-)Maghrib.

Economy

Northern Africa under Roman rule.

The principal exports from Caesariensis were purple dyes and valuable woods; and the Amazigh or Mauri were highly regarded by the Romans as soldiers, especially light cavalry. They produced one of Trajan's best generals, Lusius Quietus, and the emperor Macrinus.